FlatTableProjection example from docs fails to run about marten

[gfoidl]

Workaround is to just specify the column-name explicitly:

map.Map(x => x.ActivityType, "activity_type").NotNull();
map.Map(x => x.CustomerId, "customer_id");

But it still fails at runtime with:

23502: null value in column "activity_type" of relation "import_history" violates not-null constraint

DETAIL: Failing row contains (51a74c7b-f5da-4790-98d8-12b950f26014, null, null, 0, null, working, 0, 3, null).
 ---> Npgsql.PostgresException (0x80004005): 23502: null value in column "activity_type" of relation "import_history" violates not-null constraint

Removing the NotNull() constraint makes it run -- but the NotNull can make sense to have (depending on busines case).

[jeremydmiller]

I'm switching the naming strategy to using Posgresql friendly snake casing. Dumb mistake on my part.

Projections need to run pretty simply, and there's very little recourse for error handling other than to retry a page of events or pause the projection for manual intervention. Using any kind of database constraint that can fail from bad data has had adverse effects and can make your system brittle.